Asphaltene based photovoltaic devices

ABSTRACT

Photovoltaic devices and methods of making the same are disclosed herein. The cell comprises: a first electrically conductive layer; at least one photoelectrochemical layer comprising metal-oxide particles, an electrolyte solution, an asphaltene dye, and a second electrically conductive layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 61/224,791 filed Jul. 10, 2009, the entire contents of which isincorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates in general to the field of photovoltaicdevices.

STATEMENT OF FEDERALLY FUNDED RESEARCH

None.

BACKGROUND OF THE INVENTION

Without limiting the scope of the invention, its background is describedin connection with the dye-sensitized solar cells.

United States Patent Application No. 20090114283, filed by Lee, et al.,is directed to a dye-sensitized solar cell that includes a firstsubstrate, a first electrode layer, a photosensitive dye layer, anelectrolyte layer, a second electrode layer, and a second substrate. Thefirst electrode layer is disposed on the first substrate. Thephotosensitive dye layer is disposed on the first electrode layer. Theelectrolyte layer is disposed on the photosensitive dye layer, and theelectrolyte layer is composed of an organic electrolyte material. Thesecond electrode layer is disposed on the electrolyte layer, and thesecond substrate is disposed on the second electrode layer. A stable andeffective oxidation and reduction reaction is performed between theelements by the characteristics of the composition and the structure ofthe electrolyte material, thus improving the photoelectric conversionefficiency and the stability of the dye-sensitized solar cell.

United States Patent Application No. 20070251574, filed by Fujimaki, etal., is directed to a dye-sensitized solar cell that includes a firstelectrode having a photoelectric conversion layer, a second electrodedisposed so as to oppose the first electrode, and electrolyte filled atleast in between the first electrode and second electrode, the firstelectrode is constructed with a plurality of first electrode layersdisposed superposed in a direction that is opposite the secondelectrode.

United States Patent Application No. 20040211461, filed by Murai, etal., is also directed to a dye-sensitized solar cell. Briefly, theinvention is a dye-sensitized solar cell comprising a semiconductorelectrode containing a dye and carboxylic compound, the dye andcarboxylic compound being carried on a surface of the semiconductorelectrode, a counter electrode, and an electrolyte composition providedbetween the semiconductor electrode and the counter electrode, andcontaining an electrolyte that contains iodine and molten salt ofiodide.

U.S. Pat. No. 7,332,782, issued to Tomita is directed to adye-sensitized solar cell with high conversion efficiency. Briefly, thedye-sensitized solar cell has, between an electrode (2) formed on asurface of a transparent substrate (1) and a counter electrode (6), alight-absorbing layer (3) containing light-absorbing particles carryingdye and an electrolyte layer (5), characterized in that thelight-absorbing layer (3) containing light-scattering particles (4)different in size from the light-absorbing particles. In such adye-sensitized solar cell according to the present invention, the energyof light, which passes through a light-absorbing layer in a conventionalcell structure, can be strongly absorbed by the dye in thelight-absorbing layer of the present invention. This will increase theconversion efficiency and output current of the dye-sensitized solarcell.

U.S. Pat. No. 7,118,936, issued to Kobayashi, et al., is directed to anorganic dye-sensitized metal oxide semiconductor electrode andmanufacture and organic dye-sensitized solar cells. Briefly, asemiconductor electrode of organic dye-sensitized metal oxide having asemiconductor layer of metal oxide is said to be easily prepared for anorganic dye-sensitized solar cell. The semiconductor electrode oforganic dye-sensitized metal oxide comprises a substrate having atransparent electrode thereon, a semiconductor layer of metal oxideprovided on the electrode and an organic dye absorbed on a surface ofthe semiconductor layer, the semiconductor layer being formed by a vapordeposition process.

U.S. Pat. No. 6,479,745, issued to Yamanaka, et al., is directed to adye-sensitized solar cell and method of manufacturing the same. Briefly,the dye-sensitized solar cell comprises a porous semiconductor layer inwhich a dye is adsorbed and an electrolyte, which are sandwiched betweena transparent conductive film formed on a surface of a transparentsubstrate and a conductive substrate, wherein the electrolyte isretained in a crosslinked polymer compound.

SUMMARY OF THE INVENTION

The present invention describes a photovoltaic device and methods ofmaking a photovoltaic cell comprising: a first electrically conductivelayer; at least one photoelectrochemical layer comprising metal-oxideparticles, an electrolyte solution and an asphaltene dye; and a secondelectrically conductive layer. In certain aspects, the present inventioncan be used to make a novel excitonic device, which does not require theuse of an electrolyte.

In one embodiment the present invention is a photovoltaic devicecomprising a first electrically conductive layer at least onephotoelectrochemical layer comprising metal-oxide particles, anelectrolyte solution and an asphaltene dye and a second electricallyconductive layer comprising one or more conductive elements. In oneaspect of the photovoltaic device of the present invention themetal-oxide particles comprise titanium dioxide or other photocatalyticmaterials optionally dispersed in a surfactant, wherein the surfactantsare selected from a group comprising Triton, alkyl polyoxides,alkylphenols, alkyl polyglucosides, fatty alcohols, polysorbates, andother non-ionic surfactants.

In another aspect the one or more conductive elements comprise carbon,graphite, soot, carbon allotropes, or any combinations thereof and thefirst, second or both electrically conductive layers are flexible metalwherein the first, second of both electrically conductive layerscomprises platinum coated indium-tin oxide glass. In yet another aspectthe photoelectrochemical layer is defined further as a comprising asemiconductor material and the electrolyte solution comprises iodidesalt and iodine. The first electrically conductive layer of thephotovoltaic cell of the present invention comprises a photo-sensitizedelectrode, and the second electrically conductive layer acounter-electrode.

In another embodiment the photovoltaic cell of the present inventioncomprises a first electrically conductive layer, at least onesemiconductor layer comprising asphaltene dye-sensitized titaniumdioxide particles in an electrolyte, wherein the electrolyte comprisesiodide salt and iodine, and a second electrically conductive layercomprising at least one or more conductive elements, wherein theconductive element comprises soot.

In one aspect the metal-oxide particles comprise titanium dioxide orother photocatalytic materials optionally dispersed in a surfactantselected from a group comprising Triton, alkyl polyoxides, alkylphenols,alkyl polyglucosides, fatty alcohols, polysorbates, and other non-ionicsurfactants. In another aspect the one or more conductive elementscomprise carbon, graphite, soot, carbon allotropes, or any combinationsthereof. The first, second or both electrically conductive layers areflexible metal comprising of platinum coated indium-tin oxide glass. Thephotoelectrochemical layer of the photovoltaic cell of the presentinvention is defined further as a comprising a semiconductor material.The electrolyte solution comprises iodide salt and iodine. The firstelectrically conductive layer comprises a photo-sensitized electrode,and the second electrically conductive layer a counter-electrode.

In yet another embodiment the photovoltaic cell of the present inventioncomprises a first electrically conductive layer, at least onesemiconductor layer comprising a mixture of asphaltene andCoMoS₂-sensitized titanium dioxide particles in an electrolyte, whereinthe electrolyte comprises iodide salt and iodine and a secondelectrically conductive layer comprising one or more conductiveelements.

In one aspect the asphaltene to CoMoS₂ ratio in the mixture is 100:1,75:1, 50:1, 25:1, 10:1, 5:1, 2:1, or 1:1 and the metal-oxide particlescomprise titanium dioxide or other photocatalytic materials optionallydispersed in a surfactant and at least one semiconductor layer comprisesa mixture of asphaltene with one or more sulfides are selected from agroup comprising CoMoS₂, CdS, Cu₂S, NiMoS₂, FeMoS₂, Co, Ni, Fe, Cu andother transition metal sulfides copper indium gallium diselenide, andindium-gallium sulfide. The one or more conductive elements comprisecarbon, graphite, soot, carbon allotropes, or any combinations thereof.In another aspect the first, second or both electrically conductivelayers are a flexible metal and the first, second of both electricallyconductive layers comprises platinum coated indium-tin oxide glass. Inyet another aspect the photoelectrochemical layer is defined further asa comprising a semiconductor material and the electrolyte solutioncomprises iodide salt and iodine. The first electrically conductivelayer comprises a photo-sensitized electrode, and the secondelectrically conductive layer a counter-electrode.

In one embodiment the photovoltaic cell of the present inventioncomprises (i) a first electrically conductive layer, (ii) at least onesemiconductor layer comprising CoMoS₂-sensitized titanium dioxideparticles in an electrolyte in an electrolyte, wherein the electrolytecomprises iodide salt and iodine, and (iii) a second electricallyconductive layer comprising one or more conductive elements. In oneaspect the metal-oxide particles comprise titanium dioxide or otherphotocatalytic materials optionally dispersed in a surfactant and atleast one semiconductor layer comprises one or more sulfides selectedfrom a group comprising CoMoS₂, CdS, Cu₂S, copper indium galliumdiselenide, and indium-gallium sulfide. In another aspect the one ormore conductive elements comprise carbon, graphite, soot, carbonallotropes, or any combinations thereof and the first, second or bothelectrically conductive layers are flexible metal.

In another aspect the first, second of both electrically conductivelayers comprises platinum coated indium-tin oxide glass. In yet anotheraspect the photoelectrochemical layer is defined further as a comprisinga semiconductor material. In a certain aspect the electrolyte solutioncomprises iodide salt and iodine. The first electrically conductivelayer of the present invention further comprises a photo-sensitizedelectrode, and the second electrically conductive layer acounter-electrode.

The present invention further describes a method of making aphotovoltaic device comprising: depositing at least onephotoelectrochemical layer comprising metal-oxide particles, anelectrolyte solution and an asphaltene dye, a mixture of asphaltene anda sulfide, one or more sulfides or any combinations thereof on a firstelectrically conductive layer, and depositing a semiconductor layer on asecond electrically conductive layer. In one aspect of the method themetal-oxide particles comprise titanium dioxide or other photocatalyticmaterials optionally dispersed in a surfactant. In another aspect theone or more sulfides are selected from a group comprising CoMoS₂, CdS,Cu₂S, NiMoS₂, FeMoS₂, Co, Ni, Fe, Cu and other transition metalsulfides, copper indium gallium diselenide, and indium-gallium sulfide.In yet another aspect the semiconductor layer comprises carbon,graphite, soot, carbon allotropes, or any combinations thereof and thefirst, second or both electrically conductive layers are flexible metal.

The first, second of both electrically conductive layers comprisesplatinum coated indium-tin oxide glass and the photoelectrochemicallayer is defined further as a comprising a semiconductor material. Theelectrolyte solution comprises iodide salt and iodine and the firstelectrically conductive layer comprises a photo-sensitized electrode,and the second electrically conductive layer a counter-electrode.

The method of the present invention further comprises the steps offorming a roadway comprising the photovoltaic device by: depositing thefirst electrically conductive layer on a road bed, depositing the atleast one photoelectrochemical layer comprising metal-oxide particles,an electrolyte solution and an asphaltene dye a mixture of asphalteneand CoMoS₂, CoMoS₂ or any combinations thereof on the first electricallyconductive layer; and at least partially coating thephotoelectrochemical layer with the second electrically conductivelayer.

The present invention further describes a photovoltaic devicecomprising: a first electrically conductive layer, at least onephotoelectrochemical layer comprising metal-oxide particles, and anelectron donor substance for photon-to-current conversion, and a secondelectrically conductive layer comprising one or more conductiveelements. In one aspect the metal-oxide particles comprise titaniumdioxide or other photocatalytic materials optionally dispersed in asurfactant. The electron donor substance comprises asphaltenes, metalsulfides, mixtures of asphaltenes and metal sulfides, Ruthenium orRhodium-dye complexes, metal free dyes, or any combinations thereof. Thedevice of the present invention further comprises one or more conductiveelements comprise carbon, graphite, soot, carbon allotropes, or anycombinations thereof. The first, second of both electrically conductivelayers comprises platinum coated indium-tin oxide glass, wherein thefirst electrically conductive layer comprises a photo-sensitizedelectrode, and the second electrically conductive layer acounter-electrode.

In one embodiment the present invention describes a photovoltaic roadwaycomprising a first electrically conductive layer on a road bed, at leastone photoelectrochemical layer comprising metal-oxide particles, anelectrolyte solution and an asphaltene dye, a mixture of asphaltene andCoMoS₂, CoMoS₂ or any combinations thereof disposed on the firstelectrically conductive layer, and at least partially coating thephotoelectrochemical layer with the second electrically conductivelayer, wherein the voltage created between the first and secondelectrically conductive layers is gathered along the roadway.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of thepresent invention, reference is now made to the detailed description ofthe invention along with the accompanying figures and in which:

FIG. 1 shows a photovoltaic cell made with asphaltene solution;

FIG. 2 shows a photovoltaic cell made with asphaltene in the powderform;

FIG. 3 shows a photovoltaic cell made with a mixture of asphaltene andCoMoS₂ in the powder form;

FIG. 4 shows a photovoltaic cell made with MoS₂ in the powder form;

FIG. 5 is a graph of the IV curve of asphalthene solar cell; and

FIG. 6 is a schematic showing the conversion of light energy toelectrical energy in an asphaltene containing photovoltaic cell.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of this invention, a number of terms aredefined below. Terms defined herein have meanings as commonly understoodby a person of ordinary skill in the areas relevant to the presentinvention. Terms such as “a”, “an” and “the” are not intended to referto only a singular entity, but include the general class of which aspecific example may be used for illustration. The terminology herein isused to describe specific embodiments of the invention, but their usagedoes not delimit the invention, except as outlined in the claims.

As used herein the “photovoltaic”, also abbreviated as (PV), refers tothe direct conversion of light energy into electricity. As used herein,the term “photovoltaic device” refers to a complete set of componentsfor converting light energy into electricity by the photovoltaicprocess. The term “electrically conductive” is used herein to describe aproperty of a material that involves its ability to transferelectricity.

As used herein the term “asphaltene” refers to a high molecular weightfraction of crude oils that are insoluble in paraffinic solvents.“Asphaltenes” are characterized by a high average molecular weight(about 1000 and up to 5,000) and very broad molecular weightdistribution (up to 10,000) and high coking tendency.

The term “surfactant” used herein is intended to include compoundscommonly referred to as wetting agents, dispersing agents, andemulsification agents. Typical surfactants include thealkylarylsulfonates, the fatty alcohol sulfates, sodium salt ofnaphthalenesulfonic acid, alkylaryl polyether alcohols, long chainquaternary ammonium compounds, sodium salts of petroleum-derivedalkylsulfonic acids, polyoxyethylene-sorbitan monolaurate, and the like.These dispersing and wetting agents are sold under numerous trademarksand may either be pure compounds, mixtures of compounds of the samegeneral group, or they may be mixtures of compounds of differentclasses.

The term “semiconductor” in its broadest sense refers to a material thathas an electrical conductivity due to flowing electrons (as opposed toionic conductivity) which is intermediate in magnitude between that of aconductor and an insulator. Semiconductor devices include the varioustypes of transistor, solar cells, many kinds of diodes including thelight-emitting diode, the silicon controlled rectifier, and digital andanalog integrated circuits.

As used herein, the term “electrolyte solute” refers to a conductivespecies, such as a salt, which behaves as an electrolyte (i.e.,transports an electric current via long-range motion of ions).

The term “photocatalytic material” is used herein to refer to a materialexhibiting photocatalysis, that is, the acceleration of a chemicalreaction by radiant energy (as light) acting either directly or byexciting a substance that in turn catalyzes the main reaction.

Photovoltaic solar energy works by transforming a fraction of solarradiation into electricity by means of solar cells, which are connectedtogether to form a photovoltaic solar cell module. The solar cellscurrently on the market are made up of inorganic materials such assilicon. A great deal of research has been aimed at developing solarcells made up of organic (carbon-compound based) semiconductors.Although their performance is still considerably lower than that ofcells based on crystalline silicon (around 5% efficiency as comparedwith 15% for silicon cells), they present numerous advantages. Unlikecrystalline silicon, which has to be produced at very high temperatures,they can be manufactured cheaply with low energy cost and environmentalimpact. Moreover, the fact that they are made using solution processes(for instance from inks or paints) makes it possible to cover largeareas and flexible substrates such as films and fabrics. Organic solarcells are not intended to compete with silicon, but rather to be usedfor specific applications, such as packaging, clothing, flexiblescreens, and recharging cell phones and laptops. However, in the longerterm, they could make a significant contribution to the photovoltaicconversion of solar energy, as long as there is a continuous search fornew, more efficient and stable materials.

Over the past ten years or so, most of the research has been focused ondeveloping organic cells in which the active light-absorbing material ismade up of long conjugated polymer chains. Although these cells are themost efficient yet discovered, the use of polymers poses a certainnumber of problems: synthesis, purification, control of the molecularstructure and mass, and the distribution of different lengths of chain(polydispersity). In order to overcome these obstacles, Roncali, et al.has developed a novel approach based on replacing polymers by conjugatedmolecules with a clearly defined structure. Whereas the conversionefficiencies of the initial prototypes published in 2005 were of theorder of 0.20%, collaboration between Roncali et al. and Ziessel et al.has recently succeeded in reaching conversion efficiencies of 1.70%,which are among the highest known for this type of cell until now. Newclasses of active material specifically adapted to such cells arecurrently being synthesized in the laboratories.

The present invention may also be made as an excitonic device, whichdoes not require the use of an electrolyte. As used herein, the term“exciton” and the devices made thereby refer to a chemical configurationin which an electron is bound to a hole, in this way the exciton can bemanipulated within a semiconductor chip to and from a light source, thatis, the exciton is formed with light, processed and then converted backinto light.

FIG. 1 shows the assembly of a photovoltaic cell 2. Two pieces (4 and 6)of Indium-Tin oxide glass were used as the two electrodes for theassembly of the cell 2. The dimensions of the glass (4 and 6) were25×25×0.7 mm and they were obtained from Delta's Technologies, Limited.The bottom electrode 6 of Indium-Tin oxide was coated with Degussa 25TiO₂ 10. Degussa 25 TiO₂ 10 was mixed with Triton surfactant until theDegussa 25 TiO₂ 10 powder was paste like consistency. Then it was spreadout on the Indium-Tin oxide glass 6 and dried for 20 min at a 200° C.temperature. It was then cool down and soaked in a solution ofasphaltene (1 g)/toluene (50 mL). It was soaked for about 3 h. Then itwas pat dried. The top electrode 4 of Indium-Tin oxide was coated withsooth 8. Two electrodes 4 and 6 were sandwiched together as shown inFIG. 1. The two electrodes 4 and 6 were sandwiched together offset onefrom the other to make the contacts and measure the voltage. Twoalligator clips (not shown) were used to keep the two electrodes 4 and 6together. Then few drops of an electrolyte solution KI—ethylene glycolwere added to the edges of the cell 2. The voltage was measured with astandard voltmeter. On a sunny day it gave 0.5 volts and kept producingthe same voltage for two weeks.

FIG. 2 shows the assembly of a photovoltaic cell 14. Two pieces (16 and18) of Indium-Tin oxide glass were used as the two electrodes for theassembly of the cell 14. The dimensions of the glass were 25×25×0.7 mmand they were obtained from Delta's Technologies, Limited. The bottomelectrode 18 of Indium-Tin oxide was coated with Degussa 25 TiO₂ 22.Degussa 25 TiO₂ 22 was mixed with Triton surfactant until the Degussa 25TiO₂ 22 powder was paste like consistency. Then it was spread out on theIndium-Tin oxide glass 18 and dried for 20 min at a 200° C. temperature.It was allowed to cool down. Asphaltenes (0.001 g) were spread out onthe glass. The top electrode 16 of Indium-Tin oxide was coated withsooth 20. Two electrodes 16 and 18 were sandwiched together as shown inFIG. 2. The two electrodes 16 and 18 were sandwiched together offset onefrom the other to make the contacts and measure the voltage. Twoalligator clips (not shown) were used to keep the two electrodes 16 and18 together. Then few drops of an electrolyte solution KI—ethyleneglycol were added to the edges of the cell 14. The voltage was measuredwith a standard voltmeter. On a sunny day it gave 0.6 volts and keptproducing the same voltage for 1 week.

FIG. 3 shows the assembly of a photovoltaic cell 26. Two pieces (28 and30) of Indium-Tin oxide glass were used as the two electrodes for theassembly of the cell 26. The dimensions of the glass were 25×25×0.7 mmand they were obtained from Delta's Technologies, Limited. The bottomelectrode 30 of Indium-Tin oxide was coated with Degussa 25 TiO₂ 34.Degussa 25 TiO₂ 34 was mixed with Triton surfactant until the Degussa 25TiO₂ powder 34 was paste like consistency. Then it was spread out on theIndium-Tin oxide glass 30 and dried for 20 min at a 200° C. temperature.A mechanical mixture of asphaltene and CoMoS₂ was performed in a ratio10:1. The 0.01 g of the mixture was spread out on the Indium-Tin oxideglass 30 coated with TiO₂ 34. The top electrode 28 of Indium-Tin oxidewas coated with sooth. Two electrodes 28 and 30 were sandwiched togetheras shown in FIG. 3. The two electrodes 28 and 30 were sandwichedtogether offset one from the other to make the contacts and measure thevoltage. Two alligator clips (not shown) were used to keep the twoelectrodes 28 and 30 together. Then few drops of an electrolyte solutionKI—ethylene glycol were added to the edges of the cell 26. The voltagewas measured with a standard voltmeter. On a sunny day it gave 0.7 voltsand kept producing the same voltage for 3 weeks.

FIG. 4 shows the assembly of a photovoltaic cell 38. Two pieces (40 and42) of Indium-Tin oxide glass were used as the two electrodes for theassembly of the cell 38. The dimensions of the glass were 25×25×0.7 mmand they were obtained from Delta's Technologies, Limited. The bottomelectrode of Indium-Tin 42 oxide was coated with Degussa 25 TiO₂ 46.Degussa 25 TiO₂ 46 was mixed with Triton surfactant until the Degussa 25TiO₂ powder 46 was paste like consistency. Then it was spread out on theIndium-Tin oxide glass 42 and dried for 20 min at a 200° C. temperature.CoMoS₂ (0.01 g) was spread out on the Indium-Tin oxide glass 42 coatedwith TiO₂ 46. The top electrode 40 of Indium-Tin oxide was coated withsooth 44. Two electrodes 40 and 42 were sandwiched together as shown inFIG. 4. The two electrodes 40 and 42 were sandwiched together offset onefrom the other to make the contacts and measure the voltage. Twoalligator clips (not shown) were used to keep the two electrodes 40 and42 together. Then few drops of an electrolyte solution KI—ethyleneglycol were added to the edges of the cell 38. The voltage was measuredwith a standard voltmeter. On a sunny day it gave 0.5 volts and keptproducing the same voltage for 1 month.

IV measurements: The IV measurements were performed using a Peak PowerMeasuring Device and I-V Curve Tracer for Photovoltaic Module with thefollowing dimensions: 48×16×35 cm. There is a relationship between thecurrent-voltage obtained from solar devices. This relationship is oftenrepresented as a graph, between an electric current and a correspondingvoltage. These graphs are used to determine the basic parameters of adevice and to model its behavior in an electrical circuit. IVmeasurements were performed on the cells. FIG. 5 shows the graphcorresponding to cell 38.

FIG. 6 is a schematic representation of the mechanism by which aphotovoltaic cell containing asphaltene converts light energy toelectrical energy. The sunlight is incident on the photovoltaic cellcomprising asphlatene (electron donor) mixed in with the TiO₂. Thephotons are converted into electrons and they move from hole to hole(Ti⁺³ to Ti⁺⁴). The presence of the asphaltene in the photovoltaic cellof the present invention obviates the necessity of using an electrolyteor electrolyte solution for the transfer of the electrons.

Different organic dyes have been tested for dye sensitized solar cells.It is proposed to use asphaltenes as an organic dye. Asphaltenes haveshown to be able to produce voltage. Four different cells were tested.Asphaltene in the liquid and solid form were tested. The cells produceslightly better voltage when the asphaltene is used as a solid. This ismaybe due to the fact that in the solid form the asphaltenes are moreconcentrated that in the liquid form. It has also been observed as thelayer of asphaltene is ticker the voltage produced is better. This iscontrary to what is usually expected in ordinary dye sensitized cells.It has been reported these cells are coated using a spin coater whichprovides a really thin coating on the electrodes. Cell #3 was assembledusing CoMoS₂. It has been reported MoS₂ has solar cell applications.However, promoted systems such as CoMoS₂ and NiMoS₂ have not beenreported in the literature. Cell #3 was assembled using CoMoS₂ toimprove the conductive properties of the asphaltenes. The results showthey were improved maybe due to a synergistic effect between theasphaltenes and the catalyst. Cell #4 was assembled using only CoMoS₂and it was really stable as expected. FIG. 5 shows the IV curve of theasphalthene solar cell.

TABLE 1 Results Voltage Stability of the Cell # Assembly obtained cell 1ITO glass coated with TiO₂. Then the glass was soaked 0.5 V This cell inan asphalthene solution and pat dried. This electrode produced voltagewas assembled with the counter electrode. for 2 weeks. 2 ITO glasscoated with TiO₂ and the asphaltenes were 0.6 V This cell used in powderform. Again this electrode was produced voltage assembled with a counterelectrode. for a week. 3 ITO glass coated with TiO₂ and a mix ofasphaltenes 0.7 V This cell and CoMoS₂ in the powder form was used. Thisproduced voltage electrode was assembled with a counter electrode. for 3weeks. 4 ITO glass was coated with TiO₂ and MoS₂ in the 0.5 V This cellpowder form was used. This electrode was assembled produced voltage withthe counter electrode. for 1 month.

The results obtained using asphaltene as light harvesting materials indye sanitized solar cells are presented in Tables 2-3. Asphaltene usedbelow was hexane extracted asphaltene and the concentration was 0.25-0.5gram asphaltene/liter toluene. Asphaltene fractionation method used wastitration of asphaltene dissolved toluene with pentane till theprecipitate started appearing.

TABLE 2 Results obtained using 0.5 gram asphaltene/liter toluene. As-First Raw Raw Fourth phaltene precipitate asphaltene asphalteneprecipitate Fraction- 100 ml in benzene in toluene Sec- 200 ml ationpentane solution solution Third ond pentane Current 0.2 0.01 0.1 1.5 1.12 (mA) Voltage 11.7 2.3 7.02 1.6 1.2 5.7 (mV)

TABLE 3 Results obtained using 0.25 gram asphaltene/liter toluene. As-First Raw Raw Fourth phaltene precipitate asphaltene asphalteneprecipitate Fraction- 100 ml in benzene in toluene Sec- 200 ml ationpentane solution solution Third ond pentane Current 12 4.1 (microA)Voltage 14 4.1 (mV) Current After 7 (microA) 1 day Voltage 6.8 (mV)

TABLE 4 Results obtained using two TiO₂ layers. As- First Raw Raw Fourthphaltene precipitate asphaltene asphaltene precipitate Fraction- 100 mlin benzene in toluene Sec- 200 ml ation pentane solution solution Thirdond pentane Current 23 (microA) Voltage 52 (mV) Current After 40(microA) 1 day Voltage 273 (mV)

The results presented in Tables 2 and 3 indicate that lower asphalteneconcentration produces better quality cells. As indicated in literature,using two layers of TiO2 with different grain sizes, produce cells withhigher voltages and currents (Table 4) and leaving the cells one dayincrease the efficiency.

It is contemplated that any embodiment discussed in this specificationcan be implemented with respect to any method, kit, reagent, orcomposition of the invention, and vice versa. Furthermore, compositionsof the invention can be used to achieve methods of the invention.

It will be understood that particular embodiments described herein areshown by way of illustration and not as limitations of the invention.The principal features of this invention can be employed in variousembodiments without departing from the scope of the invention. Thoseskilled in the art will recognize, or be able to ascertain using no morethan routine experimentation, numerous equivalents to the specificprocedures described herein. Such equivalents are considered to bewithin the scope of this invention and are covered by the claims.

All publications and patent applications mentioned in the specificationare indicative of the level of skill of those skilled in the art towhich this invention pertains. All publications and patent applicationsare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one,” butit is also consistent with the meaning of “one or more,” “at least one,”and “one or more than one.” The use of the term “or” in the claims isused to mean “and/or” unless explicitly indicated to refer toalternatives only or the alternatives are mutually exclusive, althoughthe disclosure supports a definition that refers to only alternativesand “and/or.” Throughout this application, the term “about” is used toindicate that a value includes the inherent variation of error for thedevice, the method being employed to determine the value, or thevariation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

The term “or combinations thereof” as used herein refers to allpermutations and combinations of the listed items preceding the term.For example, “A, B, C, or combinations thereof” is intended to includeat least one of: A, B, C, AB, AC, BC, or ABC, and if order is importantin a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB.Continuing with this example, expressly included are combinations thatcontain repeats of one or more item or term, such as BB, AAA, MB, BBC,AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan willunderstand that typically there is no limit on the number of items orterms in any combination, unless otherwise apparent from the context.

All of the compositions and/or methods disclosed and claimed herein canbe made and executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of preferred embodiments, it will beapparent to those of skill in the art that variations may be applied tothe compositions and/or methods and in the steps or in the sequence ofsteps of the method described herein without departing from the concept,spirit and scope of the invention. All such similar substitutes andmodifications apparent to those skilled in the art are deemed to bewithin the spirit, scope and concept of the invention as defined by theappended claims.

REFERENCES

-   United States Patent Application No. 20090114283: Dye-sensitized    solar cell.-   United States Patent Application No. 20040211461: Dye-sensitized    solar cell.-   U.S. Pat. No. 7,332,782: Dye-sensitized solar cell.-   U.S. Pat. No. 7,118,936: Organic dye-sensitized metal oxide    semiconductor electrode and its manufacturing method, and organic    dye-sensitized solar cell.-   U.S. Pat. No. 6,479,745: Dye-sensitized solar cell and method of    manufacturing the same.-   Multi-donor Molecular Bulk Heterojunction Solar Cells: Improving    Conversion Efficiency by Synergistic Dye Combinations. Theodulf    Rousseau, Antonio Cravino, Thomas Bura, Gilles Ulrich, Raymond    Ziessel and Jean Roncali. Journal of Materials Chemistry. In press,    available online.-   Bodipy Derivatives as Donor Materials for Bulk Heterojunction Solar    Cells. Theodulf Rousseau, Antonio Cravino, Thomas Bura, Gilles    Ulrich, Raymond Ziessel and Jean Roncali. Chemical Communication, 19    Mar. 2009.

1. A photovoltaic device comprising: a first electrically conductivelayer comprising a photo-sensitized electrode; at least onephotoelectrochemical layer comprising metal-oxide particles, anelectrolyte solution and an asphaltene dye, wherein the metal-oxideparticles comprise a photocatalytic material optionally dispersed in asurfactant; and a second electrically conductive layer comprising acounter-electrode, wherein the second electrically conductive layercomprises one or more conductive elements comprising carbon, graphite,soot, carbon allotropes or any combinations thereof. 2.-15. (canceled)16. A photovoltaic cell comprising: a first electrically conductivelayer; at least one semiconductor layer comprising sulfide sensitizedtitanium dioxide particles in an electrolyte in an electrolyte, whereinthe electrolyte comprises iodide salt and iodine; and a secondelectrically conductive layer comprising one or more conductiveelements, wherein the one or more conductive elements comprise carbon,graphite, soot, carbon allotropes or any combinations thereof.
 17. Thephotovoltaic cell of claim 16, wherein the one or more sulfides selectedfrom a group comprising CoMoS₂, CdS, Cu₂S, NiMoS₂, FeMoS₂, Co, Ni, Fe,Cu and other transition metal sulfides, copper indium galliumdiselenide, and indium-gallium sulfide.
 18. The photovoltaic cell ofclaim 16, wherein the first, second or both electrically conductivelayers are flexible metal, wherein the first, second of bothelectrically conductive layers comprises platinum coated indium-tinoxide glass.
 19. A method of making a photovoltaic device comprising:depositing at least one photoelectrochemical layer comprisingmetal-oxide particles, an electrolyte solution and an asphaltene dye, amixture of asphaltene and a sulfide, one or more sulfides or anycombinations thereof on a first electrically conductive layer, whereinthe first electrically conductive layer comprises a photo-sensitizedelectrode; and depositing a semiconductor layer on a second electricallyconductive layer, wherein the semiconductor layer comprises carbon,graphite, soot, carbon allotropes or any combinations thereof, whereinthe second electrically conductive layer comprises a counter-electrode.20. The method of claim 19, wherein the metal-oxide particles comprisetitanium dioxide or other photocatalytic materials optionally dispersedin a surfactant.
 21. The method of claim 19, wherein the one or moresulfides are selected from a group comprising CoMoS₂, CdS, Cu₂S, NiMoS₂,FeMoS₂, Co, Ni, Fe, Cu and other transition metal sulfides, copperindium gallium diselenide, and indium-gallium sulfide.
 22. The method ofclaim 19, wherein the first, second or both electrically conductivelayers are flexible metal, wherein the first, second of bothelectrically conductive layers comprises platinum coated indium-tinoxide glass.
 23. The method of claim 19, wherein thephotoelectrochemical layer is defined further as a comprising asemiconductor material.
 24. The method of claim 19, wherein theelectrolyte solution comprises iodide salt and iodine.
 25. The method ofclaim 19, further comprising the steps of forming a roadway comprisingthe photovoltaic device by: depositing the first electrically conductivelayer on a road bed; depositing the at least one photoelectrochemicallayer comprising metal-oxide particles, an electrolyte solution and anasphaltene dye a mixture of asphaltene and CoMoS₂, CoMoS₂ or anycombinations thereof on the first electrically conductive layer; and atleast partially coating the photoelectrochemical layer with the secondelectrically conductive layer.
 26. A photovoltaic device comprising: afirst electrically conductive layer, wherein the first electricallyconductive layer comprises a photo-sensitized electrode; at least onephotoelectrochemical layer comprising metal-oxide particles, and anelectron donor substance for photon-to-current conversion; and a secondelectrically conductive counter-electrode layer comprising one or moreconductive elements; wherein the one or more conductive elementscomprise carbon, graphite, soot, carbon allotropes or any combinationsthereof.
 27. The device of claim 26, wherein the metal-oxide particlescomprise titanium dioxide or other photocatalytic materials optionallydispersed in a surfactant.
 28. The device of claim 26, wherein theelectron donor substance comprises asphaltenes, metal sulfides, mixturesof asphaltenes and metal sulfides, Ruthenium or Rhodium-dye complexes,metal free dyes or any combinations thereof.
 29. The device of claim 26,wherein the first, second of both electrically conductive layerscomprises platinum coated indium-tin oxide glass.
 30. A photovoltaicroadway comprising a first electrically conductive layer on a road bed;at least one photoelectrochemical layer comprising metal-oxideparticles, an electrolyte solution and an asphaltene dye, a mixture ofasphaltene and CoMoS₂, CoMoS₂ or any combinations thereof disposed onthe first electrically conductive layer; and at least partially coatingthe photoelectrochemical layer with the second electrically conductivelayer, wherein the voltage created between the first and secondelectrically conductive layers is gathered along the roadway.